Endless power transmission belt construction and method of making the same

ABSTRACT

An endless power transmission belt construction and method of making the same are provided, the belt construction having opposed side edges and having an inner surface defining a plurality of longitudinally disposed and alternately spaced apart projections and grooves for meshing with a ribbed surface of a rotatable pulley or the like and defining a plurality of transversely disposed and alternately spaced apart projections and grooves that respectively extend between and to the opposed side edges, the longitudinal spacings between the transverse grooves or/and the depths of the transverse grooves being staggered so as to tend to reduce noise during normal operation of the belt construction with the pulley or the like.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional patent application of its copendingparent patent application, Ser. No. 324,852, filed Mar. 17, 1989 nowU.S. Pat. No. 4,884,998, which, in turn, is a divisional patentapplication of its copending parent patent application, Ser. No.152,693, filed Feb. 5, 1988, now U.S. Pat. No. 4,832,670.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new endless power transmission beltconstruction and to a new method of making an endless power transmissionbelt construction.

2. Prior Art Statement

It is known to provide an endless power transmission belt constructionhaving opposed side edge means and having an inner surface meansdefining a plurality of longitudinally disposed and alternately spacedapart projections and grooves for meshing with a ribbed surface means ofa rotatable pulley means or the like and defining a plurality oftransversely disposed and alternately spaced apart projections andgrooves. For example, see the U.S. patent to Hull, No. 4,647,278.

It is also known to provide alternately spaced apart projections andgrooves in an endless power transmission belt construction wherein thelongitudinal spacings between the transverse grooves or/and the depthsof the transverse grooves are staggered so as to tend to reduce noiseduring normal operation of the belt construction. For example, see theU.S. patent to Imamura, No. 4,264,314.

It is also known to provide vehicle tires with treads and buildingceilings with notches that respectively have spacings or depths that arestaggered on the basis of a quadratic residue sequence based on a primenumber. For example, see the article in Science News, Vol. 129, Jan. 4,1986, pages 12-13, entitled "Acoustic Residues."

SUMMARY OF THE INVENTION

It is one feature of this invention to provide a new endless powertransmission belt construction that has a plurality of longitudinallydisposed and alternately spaced apart projections and grooves fordriving against a similarly ribbed surface means on a rotatable pulleyor the like and that has means for tending to reduce noise during normaloperation of the belt construction with that pulley or the like.

In particular, it was found according to the teachings of this inventionthat even though the belt construction of the aforementioned U.S. patentto Hull, No. 4,647,278, was provided with a plurality of transverselydisposed and alternately spaced apart projections and grooves along withthe plurality of longitudinally disposed and alternately spaced apartprojections and grooves in the inner surface means thereof, the spacingsbetween the transverse grooves and the depths of the transverse groovesare uniform. Therefore, it is believed according to the teachings ofthis invention that if the longitudinal spacings between the transversegrooves or/and the depths of the transverse grooves are staggered, suchstaggering will tend to reduce the noise created by the normal operationof the belt construction with its associated pulley or the like.

For example, one embodiment of this invention provides an endless powertransmission belt construction having opposed side edge means and havingan inner surface means defining a plurality of longitudinally disposedand alternately spaced apart projections and grooves for meshing with aribbed surface means of a rotatable pulley means or the like anddefining a plurality of transversely disposed and alternately spacedapart projections and grooves that respectively extend between and tothe opposed side edge means, the longitudinal spacings between thetransverse grooves or/and the depths of the transverse grooves beingstaggered so as to tend to reduce the noise during normal operation ofthe belt construction with the pulley means or the like.

Accordingly, it is an object of this invention to provide a new endlesspower transmission belt construction having one or more of the novelfeatures of this invention as set forth above or hereinafter shown ordescribed.

Another object of this invention is to provide a new method of making anendless power transmission belt construction, the method of thisinvention having one or more of the novel features of this invention asset forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a broken away perspective view of one of the new endless powertransmission belt constructions of this invention.

FIG. 2 is an enlarged, fragmentary, cross-sectional view taken on line2--2 of FIG. 1 and illustrating the belt construction meshing with aribbed surface means of a pulley means or the like.

FIG. 3 is an enlarged fragmentary side view of a portion of the beltconstruction of FIGS. 1 and 2.

FIG. 4 is a fragmentary bottom view of the belt construction of FIG. 3and is taken in the direction of the arrows 4--4 of FIG. 3.

FIG. 5 is a view similar to FIG. 1 and illustrates another of theendless power transmission belt constructions of this invention.

FIG. 6 is an enlarged, fragmentary, cross-sectional view taken on line6--6 of FIG. 5 and illustrates the belt construction meshing with aribbed surface means of a pulley means or the like.

FIG. 7 is a fragmentary and schematic side view illustrating howlongitudinal spacings between the transverse grooves of the beltconstruction of FIG. 5 are developed.

FIG. 8 is an enlarged fragmentary side view of the belt construction ofFIG. 5 and illustrates one complete sequence of the staggered pattern ofthe longitudinal spacings between the transverse grooves thereof.

FIG. 9 is a fragmentary bottom view of the belt construction illustratedin FIG. 8 and is taken in the direction of the arrows 9--9 of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the various features of this invention are hereinafter illustratedand described as being particularly adapted to provide an endless powertransmission belt construction having longitudinal ribs or projectionson the bottom surface means thereof for meshing with similar ribbedstructure on a rotatable pulley, it is to be understood that the variousfeatures of this invention can be utilized singly or in variouscombinations thereof to provide an endless power transmission beltconstruction for operating on other surface means as desired.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIGS. 1--4, a new endless power transmission beltconstruction of this invention is generally indicated by the referencenumeral 20 and comprises an outer tension section 21, an innercompression section 22 and a load carrying section 23 secured to anddisposed intermediate the tension section 21 and the compression section22, the sections 21, 22 and 23 of the belt construction 20 being formedof conventional materials, such as mainly of polymeric materials, and ina conventional manner as is well known in the art of making endlesspower transmission belt construction whereby such materials and methodsneed not be specifically described as the same are well known in theart.

The inner compression section 22 of the belt construction 20 has aninner surface means 24 defining, in a manner hereinafter set forth, aplurality of longitudinally disposed and alternately spaced apartprojections 25 and grooves 26 that are disposed substantially parallelto each other throughout the entire endless length thereof and aplurality of transversely disposed and alternately spaced apartprojections 27 and grooves 28 that are disposed substantially parallelto each other throughout the longitudinal length of the beltconstruction 20 and that respectively extend between and to opposed sideedge means 29 of the belt construction 20, the transverse projections 27and grooves 28 being disposed substantially perpendicular to thelongitudinal projections 25 and grooves 26 and forming a pattern in thesurface means 24 as best illustrated in FIGS. 3 and 4.

As previously stated, it is known from the aforementioned U.S. patent toHull, No. 4,647,278 to provide an endless belt construction havinglongitudinal and transversely disposed projections and grooves with thelongitudinal projections and grooves meshing with a ribbed ormulti-grooved surface means on a rotatable pulley or the like fortransmitting motion therebetween and with the transverse projections andgrooves providing flexibility to such belt construction whereby thispatent to Hull, U.S. Pat. No. 4,647,278, is being incorporated into thisdisclosure by this reference thereto.

As illustrated in FIG. 2, the belt construction 20 of this invention isillustrated as engaging against a surface means 30' of a rotatablepulley 30, the surface means 30' of the pulley 30 having a plurality ofalternately spaced apart projections 31 and grooves 32 that respectivelymesh with the longitudinally disposed grooves 26 and projections 25 onthe inner surface means 24 of the belt construction 20 so as to transmitdriving movement therebetween while preventing lateral movement betweenthe belt construction 20 and the member 30 relative to each other in amanner well known in the art, such an arrangement being fully disclosedin the U.S. patent to Waugh, No. 2,802,511, whereby this patent is beingincorporated into this disclosure by this reference thereto.

However, it is believed according to the teachings of this inventionthat since the transverse projections of the aforementioned U.S. patentto Hull, No. 4,647,278, are uniformly spaced apart and have uniformdepths throughout the longitudinal length of the belt construction,there is a tendency for such prior known belt construction to produce anadverse noise when running against the surface means 30' of the pulleymeans 30.

It is well known from the aforementioned patent to Imamura, U.S. Pat.No. 4,264,314, that operating noise of an endless belt construction thathas its opposed side edge means engaging against angled sheave surfacesof a pulley construction can have the operating noise thereof reduced ifsuch belt construction is provided with alternately spaced aparttransverse projections and grooves that are disposed substantiallyparallel to each other but with the longitudinal spacings between thetransverse grooves or/and the depths of the transverse grooves beingstaggered whereby this patent to Imamura, U.S. Pat. No. 4,264,314 isbeing incorporated into this disclosure by this reference thereto.

Accordingly, it is believed according to the teachings of this inventionthat the transverse grooves 28 of the belt construction 20 of thisinvention should have the longitudinal spacings therebetween or/and thedepths of the transverse grooves 28 staggered to tend to reduce thenoise of such a longitudinally grooved or ribbed belt constructionoperating with a ribbed surface of a pulley means or the like.

In particular, it is believed that such staggered relationship can bebased on an acoustic phase grating generated from a quadratic residuesequence such as set forth in the aforementioned Science News article"Acoustic Residues" whereby this article is being incorporated into thisdisclosure by this reference thereto.

For example, the specific pattern shown in FIGS. 1-4 for staggering thedepths of the grooves 28 has a depth d for each transverse groove 28which is generated by multiplying m by the remainder left after squaringthe sequence number (n equals 1, 2, 3, 4, etc.) of that groove 28 anddividing by the generating number, such as 17 (in mathematical notation,d=m.(n² MOD17)) where m equals maximum groove depth divided by thegenerating number minus one. The multiple m could be any empiricallychosen number such that normally the maximum groove depth is within therange of approximately 40% to 70% of the belt thickness, depending uponcord location.

While the longitudinal spacings s illustrated in FIGS. 3 and 4 betweenadjacent transverse grooves 28 are uniformly spaced, it is to beunderstood that the same could be randomly staggered if desired.Alternately, the longitudinal spacings s between the adjacent grooves 28could be varied at random or by a generator function similar to the onediscussed above for the depths d thereof or by other means as desired.

While it should be appreciated that the most effective reflection phasegrating is based on a quadratic residue sequency based on the primenumber 17, other generators may also be feasible. For example, sequencesbased on the prime sequence 17, 19, 23 are known to be useful forreducing generated noise in the tire industry. Higher order generatorsmay also be useful, such as the function based on n³.

As previously stated, the surface means 24 of the belt construction 20could be formed in any suitable manner, such as being formed by firstmolding the transverse projections 27 and grooves 28 into thecompression section 22 by utilizing an internally ribbed curing jacketthat was compressed against the compression section 22 by steam andpressure in a conventional manner of forming a bottom cogged or bottomtoothed belt construction during a heat curing operation on the beltconstruction. For example, see the aforementioned U.S. patent to Waugh,No. 2,802,511.

Thereafter, the longitudinally disposed projections 25 and grooves 26can be cut into the thus molded and cured belt construction 20 by a flycutting operation as fully disclosed and claimed in the patent to Hetz,U.S. Pat. No. 2,496,269 whereby this patent is being incorporated intothis disclosure by this reference thereto.

However, it is believed according to the teachings of this inventionthat the building of the belt construction 20 of this invention and theforming of the transverse projections 27 and grooves 28, as well as theforming of the longitudinally disposed projections 25 and grooves 26could be made in other manners as desired.

For example, it is believed that the longitudinally disposed projections25 and grooves 26 could be molded at the same time that the transverseprojections 27 and grooves 28 are being molded into the compressionsection 22.

Also, it is believed that the longitudinally disposed projections 25 andgrooves 26 could be cut by a grinding operation rather than by a millingoperation if desired.

In one working embodiment of the belt construction 20 of this invention,the belt construction 20 has a standard longitudinally ribbedarrangement, such as set forth in the aforementioned patent to Hull,U.S. Pat. No. 4,647,278, wherein the depth 32 (FIG. 2) of eachlongitudinal groove 26 is approximately 0.95 (plus or minus 0.010) of aninch and the pitch or transverse distance 33 between the center lines 34of adjacent grooves 26 is approximately 0.140 (plus or minus 0.002) ofan inch. The bottom 35 of each longitudinal groove 26 is defined by aradius of approximately 0.004 (plus or minus 0.002) of an inch while thelongitudinal projections 25 each has a substantially flat free endsurface 36 that is not cut away and thereby is as molded. However, thecutting operation to form the longitudinal projections 25 and grooves 26causes the projections 25 to have substantially flat facing faces 37therebetween of approximately 40° (plus or minus 2.8°). Also, suchcutting operation for forming the longitudinal projections 25 andgrooves 26 forms the opposed ends 36' of the free ends 36 of theprojections 25 to each have a radius of approximately 0.010 (plus orminus 0.002) of an inch.

Such working embodiment of the belt construction 20 has a maximum depthd for the transverse grooves 28 of approximately 0.136 of an inchwhereby the average depth is approximately 0.068 of an inch. The spacings is uniform and is approximately 0.306 of an inch while the facingsides of adjacent transverse projections make an angle of approximately30°. The length of the belt construction is approximately 20.808 inchesand therefore has four repeating sequences therein for the staggereddepth pattern thereof.

Another endless power transmission belt construction of this inventionis generally indicated by the reference numeral 20A in FIGS. 5-9 andparts thereof similar to like parts of the belt construction 20previously described are indicated by like reference numerals followedby the reference letter "A".

As illustrated in FIGS. 5-9, the belt construction 20A has its innersurface means 24A provided with the plurality of alternately spacedapart projections 25A and grooves 26A for meshing with the grooves 32Aand projections 31A on the pulley means 30A for the reasons previouslyset forth, the inner surface means 24A also having a plurality oftransversely disposed and alternately spaced apart projections 27 andgrooves 28 wherein the spacings sA between adjacent grooves 28A arestaggered so as to tend to reduce noise during normal operation of thebelt construction 20A with the pulley means 30A for the reasonspreviously set forth.

In fact, the matrix which forms the transverse projections 27A andgrooves 28A of one working embodiment of the belt construction 20A ofthis invention is based on a like matrix that has been utilized in thepast to form transverse grooves and projections in the inner surfacemeans of an endless belt construction that drives through its angledside edges in substantially the same manner as the aforementioned U.S.patent to Imamura, No. 4,264,314.

In particular, it can be seen in FIG. 7 that the transverse projections27A for the belt construction 20A are formed from having the adjacenttransverse grooves 28A thereof spaced apart by five different spacings40, 41, 42, 43 and 44 respectively being defined by lines A, B, C, D,and E as illustrated. By so arranging the spacings 40-44, a generallyrandom staggered spacing sA arrangement can comprise a sequence of 34spacings A-E with the belt construction 20A then having a repeating ofsuch a sequence of spacings over and over again throughout the entirelongitudinal length of the belt construction 20A. In the one workingembodiment of the belt construction 20A, each sequence comprises thefollowing order: AECCDBCBDCEABBCADCEBADDBECBEADCBDC.

Such working embodiment of the belt construction 20A of this inventionhas the length of the spacings 40-44 respectively as 0.250 of an inch;0.281 of an inch; 0.313 of an inch; 0.344 of an inch and 0.375 of aninch while the average depth T, FIG. 7, of each transverse groove 28A isapproximately 0.105 of an inch with the radius R2 and R3 illustrated inFIG. 7 each being approximately 0.045 of an inch. Such workingembodiment of the belt construction 20A has the dimensions of thelongitudinal projections 25A and grooves 26A formed in the same manneras the projections 25 and grooves 26 previously set forth and will notbe repeated and like reference numerals of FIG. 2 are utilized in FIG. 6except that the same are followed by the reference letter "A".

However, it is to be understood that while certain specific dimensionshave been previously set forth for the belt constructions 20 and 20A,this was merely for example only and not to be a limitation on theclaimed inventions.

Thus, it can be seen that this invention not only provides a new endlesspower transmission belt construction, but also this invention provides anew method of making an endless power transmission belt construction.

While the forms and methods of this invention now preferred have beenillustrated and described as required by the Patent Statute, it is to beunderstood that other forms and method steps can be utilized and stillfall within the scope of the appended claims wherein each claim setsforth what is believed to be known in each claim prior to this inventionin the portion of each claim that is disposed before the terms "theimprovement" and sets forth what is believed to be new in each claimaccording to this invention in the portion of each claim that isdisposed after the terms "the improvement" whereby it is believed thateach claim sets forth a novel, useful and unobvious invention within thepurview of the Patent Statute.

What is claimed is:
 1. In an endless power transmission beltconstruction having opposed side edge means and having an inner surfacemeans for engaging a surface means of a rotatable pulley means or thelike and defining a plurality of transversely disposed and alternatelyspaced apart projections and grooves that respectively extend betweenand to said opposed side edge means, the improvement wherein the depthsof said transverse grooves are staggered so as to tend to reduce noiseduring normal operation of said belt construction with said pulley meansor the like, said depths being staggered in a sequence calculated from ageneral formula utilizing a certain generating number with that sequencethen being repeated throughout the length of said belt construction inthe longitudinal direction thereof, said depths of said transversegrooves in each sequence thereof being staggered on the basis of aguadratic residue sequence based on said certain generating number wherethe depth for each transverse groove in each sequence thereof isdetermined by multiplying m (where m is the maximum desired depthdivided by the generating number minus one) times the integer remainderafter taking the quotient of the square of the sequence number dividedby the generating number.
 2. A belt construction as set forth in claim 1wherein the longitudinal spacings between said transverse grooves arestaggered in a generally randomly manner.
 3. A belt construction as setforth in claim 2 wherein the average length of said longitudinalspacings is between approximately 0.3 of an inch and approximately 0.4of an inch.
 4. A belt construction as set forth in claim 3 wherein saidaverage length is approximately 0.313 of an inch.
 5. A belt constructionas set forth in claim 4 wherein said longitudinal spacings comprise fivedifferent lengths that are arranged in a random sequence or a certainnumber of said lengths with that sequence then being repeated throughoutthe length of said belt construction in the longitudinal directionthereof.
 6. A belt construction as set forth in claim 1 wherein saidcertain generating number is a prime number other than
 1. 7. In anendless power transmission belt construction having opposed side edgemeans and having an inner surface means for engaging a surface means ofa rotatable pulley means or the like and defining a plurality oftransversely disposed and alternately spaced apart projections andgrooves that respectively extend between and to said opposed side edgemeans, the improvement wherein the depths of said transverse grooves arestaggered so as to tend to reduce noise during normal operation of saidbelt construction with said pulley means or the like, said depths beingstaggered in a certain sequence with that sequence then being repeatedthroughout the length of said belt construction in the longitudinaldirection thereof, said depths of said transverse grooves in eachsequence thereof being staggered on the basis of a quadratic residuesequence based on a prime number where the depth for each transversegroove in each sequence thereof is determined by multiplying theremainder of the prime number subtracted from the value of the maximumdesired depth times the square of the sequence number of that particulartransverse groove divided by the prime number.
 8. A belt construction asset forth in claim 7 wherein said certain prime number is
 17. 9. A beltconstruction as set forth in claim 6 wherein the longitudinal spacingsbetween said transverse grooves are staggered.